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BIOLOGY

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Saturday, March 5, 2016

A TREAT FOR MOSQUITOES-TEXT

A TREAT FOR MOSQUITOES

ENVIRONMENTAL
STUDIES

CBSE-V

Mosquitoes
are small, midge-like flies which comprise the family Culicidae. Females of
most species are ectoparasites, whose tube-like mouthparts pierce the hosts'
skin to consume blood. The word "mosquito" is Spanish for
"little fly".

Mosquitoes
have six legs. They also have a head, thorax and abdomen. Mosquitoes can't fly very far or very
fast.

The Anophelesis
a malaria carrier, and the other two are known to spread various forms of
encephalitis. Only female mosquitoes bite and suck the blood.

Both
male and female feed mainly on fruit and plant nectar, but the female also
needs the protein in blood to help her eggs develop. Once she's had her fill of
blood, she'll rest for a couple of days before laying her eggs.

Male
mosquitoes indentify females
mosquitioes by the sound of their
wings. Females can beat their wings up to 500 times per second.

Mosquitoes
can smell human breatha. They have receptors on their antennae that detect the
carbon dioxide released when we exhale. There are more than 3,500 species of mosquitoes.

Malaria is caused by a parasite that lives in
mosquitoes. The parasite gets into mosquito saliva and is passed on
when the insect bites someone. Mosquitoes are considered the deadliest “animal”
in the world.

The Anopheles mosquito,
in particular, is dangerous because it transmits malaria, which kills more than
one million people every year, primarily in Africa.

Blood
test:

Rajat
is back at school today. He had been absent for many days. “How are you now?”
asked Aarti. “I’m alright,” Rajat replied softy.

Jaskirat:
You must have played a lot while you were at home.

Rajat
: Who wants to play when you have fever! On top of it I had to take a bitter
medicine! I even had a blood test.

Jaskirat:
A blood test? Why? It must have been very painful.

Rajat:
Actually, when the needle pricked my finger, it felt like an ant bite. They
took 2-3 drops of blood, and sent it for testing. That’s how we came to know
that I had malaria.

Nancy:
But you get malaria when a mosquito bites you.

Rajat:
Yes, but we find out by the blood test.

Jaskirat:
There are a lot of mosquitoes in my house these days, but I did not get
malaria.

Nancy:
Who says that every mosquito bite causes malaria? Malaria spreads only by the
disease carrying mosquitoes.

Aarti:
All mosquitoes look the same to me.

Rajat:
There must be some difference.

Dr
Maryam looking at the blood slide under the microscope. This miscroscope makes
things look thousand times bigger. The details inside the blood can be seen clearly.
There are some miscroscopes which make things look even more bigger than this one.

Nancy:
Did they take the blood from the place where the mosquito

had
bitten you?

Rajat:
Of course not! How do I know when and where the mosquito bit me?

Nancy:
But how could they find out that you had malaria by your blood test? Do you
think they could see something in the blood?

Medicine
for Malaria

From
early times, the dried and powdered bark of the Cinchona tree was used to make
a medicine for malaria. Earlier people used to boil the bark powder and strain
the water which was given to patients. Now tablets are made from this.

Anaemia–What’s
that?

Aarti:
You know, I also had to get a blood test done. But they took

a
syringe full of blood. The blood test showed that I had anaemia.

Rajat:
What is that?

Aarti:
The doctor said that there is less ‘haemoglobin’ or iron in the blood. The
doctor gave some medicines to give me strength. He also said that I should eat
jaggery, amla and more green leafy vegetables, because these have iron.

Nancy:
How can there be iron in our blood?

Jaskirat:
There was something about this in the newspaper

yesterday.

Rajat
(laughing) : So then you ate iron or what?!

Aarti:
Silly! This is not the iron used to make these keys. I don’t know exactly what
it was. After I ate a lot of vegetables and whatever the doctor had said, my
haemoglobin went up.

Anaemia
common in Delhi school -17 November, 2007 – Thousands of children studying in
the Municipal Corporation schools in Delhi suffer from anaemia. This is
affecting both their physical as well as mental health.

Due
to anaemia, children do not grow well, and their energy levels are low. This
also affects their ability to study properly. Now health check ups are being
done in the schools and health cards are being made for all the children. Anaemic
children are also being given iron tablets.

Baby
mosquitoes

Jaskirat:
There is a poster on malaria just outside our class.

Rajat:
The poster says something about larvae. What are those?

Nancy:
They are baby mosquitoes. But they don’t look like mosquitoes at all.

Aarti:
Where did you see them?

Nancy:
There was an old pot lying behind our house. It was full of water for some
days. When I looked there I saw some tiny thread-like grey things swimming. I
was surprised when Mummy told me that these had come out of the eggs which
mosquitoes lay in water. They are called larvae. I also heard something about
this on the radio.

Rajat:
What did you do?

Nancy:
Papa immediately threw away the water. He cleaned and dried the pot and kept it
upside down, so that no water would collect.

Survey
report Some children did this survey. Here are some of their reports We found something green around the taps in
our school which is called algae. It was also slippery there. The algae spreads
a lot during the rainy season. We think that they are some kind of small plants
that grow in water.

There
is a pond near the school. At first you cannot see the water in the pond as it
is completely covered with plants. One aunty told us that t h e s e p l a n t s
have grown themselves in water.

Around
the pond there are pits full of water. We also saw some larvae in the water. As
we moved around, lots of mosquitoes flew from the plants growing around.
Jaskirat feels that there are so many mosquitoes in her house because of this
dirty pond nearby.

A
scientist peeps into a mosquito’s stomach

This
interesting incident took place almost a hundred years ago. A

scientist
found out that mosquitoes spread malaria. Let's read about

this
discovery in his own words.

“My
father was a general in the Indian Army. I studied to become a

doctor,
but what I really liked was reading stories, writing poetry, music

Ronald
Ross and drama. In my free time I enjoyed doing all this.

In
those days, thousands of people used to die from a disease that we now call malaria.
The disease was found in areas where there was a lot of rain, or in swampy places.

People
thought that the illness was caused by some poisonous gas that came from the
dirty swampy areas. They gave it the name 'malaria' which means 'bad air'.

One
doctor had seen tiny germs in the blood of one of the patients, when he
observed it under a microscope. But he could not understand how these had got into
the patient’s blood.

My
professor had some ideas about this. “I think that these may be carried by some
kind of mosquito.” As his student, I spent all my time chasing mosquitoes, to catch
and observe. We used to carry empty bottles and chase mosquito after mosquito.

Then
we would put the mosquitoes into a mosquito net in which there was a patient of
malaria. The mosquitoes would have a feast, biting these patients.

The
patients were paid one anna for allowing one mosquitoe to bite them. I will
always remember those days at the hospital in Secundrabad – how we used to cut
open the mosquito’s stomach and peep into it.

I
would spend hours and hours bent over the microscope. By night my neck would be
stiff and my eyes could not see clearly! It used to be very hot but we dared
not fan ourselves, as all the mosquitoes would fly off in the breeze! Once I
also fell ill with malaria.

I
spent months like this with the microscope, but could not find anything. One day
we caught a few mosquitoes that looked different. They were brownish with spotted
wings.

When
I looked into the stomach of one of the female mosquitoes, I saw something
black there. I looked closer. I saw that these tiny germs looked just like the
ones that were found in the blood of malaria patients.

At
last we had the proof! Mosquitoes did spread malaria!” In December 1902, Ronald
Ross got the highest award for his discovery—the Nobel Prize for medicine. In
1905, even as he lay dying, Ross’s last words were, “I will find something, I
will find something new.”

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About Me

Nanditha completed her Masters in Zoology, English, Education. She is multifaceted and has an abiding interest in children and education. She is a vibrant and enthusiastic teacher and has a unique ability to draw the attention of children to the subject at hand. Her primary goal is to carry out deep studies on the effect of a child centric and holistic education on students. Herself a skilled teacher in multiple subjects she wants her researches to sensitize the world to the infinite powers inherent in the child.